public Map<String, Object> execute(Environment environment) throws Exception {
Map<String, Object> variables = new HashMap<String, Object>();
DbSession dbSession = environment.get(DbSession.class);
ClientExecution execution = dbSession.findExecutionById(executionId);
for (String variableName : variableNames) {
Object value = execution.getVariable(variableName);
variables.put(variableName, value);
}